1. Field of the Invention
This invention relates to a tape printing apparatus which is capable of printing on a printing tape while feeding the printing tape from a tape cartridge loaded therein and cutting off the printed portion of the printing tape.
2. Prior Art
In a conventional tape printing apparatus, a tape cartridge containing a roll of a printing tape and a roll of an ink ribbon is removably loaded in a main unit of the apparatus. The main unit contains a print head which faces the tape cartridge loaded in the main unit, a tape feed mechanism for simultaneously feeding both the printing tape and the ink ribbon, and a tape cutting mechanism for cutting off a printed portion of the printing tape. The tape feed mechanism feeds the printing tape and the ink ribbon in a state placed one upon the other, and the print head faces toward the printing tape and the ink ribbon fed by the tape feed mechanism, for printing on the printing tape as desired. During the printing operation, used part of the ink ribbon is taken up within the tape cartridge, and a printed portion of the printing tape alone is sent out of the main unit via a tape exit. When the printing operation is completed, the printed portion of the printing tape is cut off by the tape cutting mechanism and discharged from the apparatus. The tape feed mechanism and the tape cutting mechanism each include a motor as a drive source, and are subject to centralized control by a controller.
In the above conventional tape printing apparatus, the tape feed mechanism and the tape cutting mechanism as output ends of the driving system of the apparatus are different in the manner and timing of operation, and therefore the two mechanisms are required to be driven by respective different motors. This results in an increase in the number of component parts and space for installation of the same.
It is an object of the invention to provide a tape printing apparatus which is capable of properly operating a tape feed mechanism and a tape cutting mechanism by the use of a single motor.
To attain the above object, the present invention provides a tape printing apparatus a tape printing apparatus which is capable of printing on a printing tape while feeding the printing tape by unwinding a roll of the printing tape, and cutting off a printed portion of the printing tape.
The tape printing apparatus according to the invention is characterized by comprising:
a tape feed mechanism for feeding the printing tape;
a tape cutting mechanism for cutting the printing tape;
a single motor which is capable of performing rotation in normal and reverse directions;
a first torque transmitting mechanism for transmitting torque of the motor to the tape feed mechanism to cause the tape feed mechanism to operate;
a second torque transmitting mechanism for transmitting the torque of the motor to the tape cutting mechanism to cause the tape cutting mechanism to operate; and
a clutch mechanism interposed between the motor, and the first torque transmitting mechanism and the second torque transmitting mechanism, for performing switching operation to selectively transmit the torque of the motor in one of the normal and reverse directions to the first torque transmitting mechanism, and the torque of the motor in another of the normal and reverse directions to the second torque transmitting mechanism.
According to this tape printing apparatus, when the motor performs normal rotation, for instance, the torque of the motor is transmitted by the clutch mechanism via the first torque transmitting mechanism to the tape feed mechanism to feed the tape, while when the motor performs reverse rotation, the torque of the motor is transmitted by the clutch mechanism via the second torque transmitting mechanism to the tape cutting mechanism to cut off the printed portion of the tape. That is, it is possible to feed the printing tape by rotation of the motor in one direction and cut off the printed portion of the tape by rotation of the same in the other direction.
Preferably, the tape printing apparatus includes an output gear from which the torque of the motor is output, and a rotational shaft on which the output gear is rigidly fitted, the first torque transmitting mechanism including a feed mechanism-side gear train for transmitting the torque of the motor to the tape feed mechanism, the feed mechanism-side gear train having an input gear, the second torque transmitting mechanism including a cutting mechanism-side gear train for transmitting the torque of the motor to the tape cutting mechanism, the cutting mechanism having an input gear, the clutch mechanism including a planet gear mating with the output gear, and a carrier having one end thereof supporting the planet gear such that the planet gear is rotatable thereon and another end thereof loosely fitted on the rotational shaft on which the output gear is rigidly fitted such that the carrier is capable of pivotal movement, by frictional drag, with rotation of the rotational shaft, the planet gear being mated with the input gear of the feed mechanism-side gear train by the rotation of the motor in the one of the normal and reverse directions, and mated with the input gear of the cutting mechanism-side gear train by the rotation of the motor in the another of the normal and reverse directions.
According to this preferred embodiment, when the motor performs the normal rotation, for instance, the carrier of the clutch mechanism pivotally moves or swings in one direction, by frictional drag, with rotation of the rotational shaft on which the output gear is fitted to cause the planet gear to automatically mate with the input gear of the feed mechanism-side gear train, whereby torque of the output gear is transmitted to the input gear of the feed mechanism-side gear train via the planet gear. On the other hand, when the motor performs the reverse rotation, the carrier of the clutch mechanism pivotally moves or swings in the other direction, by frictional drag, with rotation of the rotational shaft on which the output gear is fitted to cause the planet gear to automatically mate with the input gear of the cutting mechanism-side gear train, whereby the torque of the output gear is transmitted to the input gear of the cutting mechanism-side gear train via the planet gear. As described above, the switching between the normal and reverse rotations of the motor causes automatic switching of the clutch mechanism, and hence the supply of the driving force can be automatically switched. Further, the use of the planet gear permits the clutch mechanism to be simplified in construction.
Preferably, the tape printing apparatus includes an ink ribbon to be fed in a state placed upon the printing tape, the tape feed mechanism including a platen for feeding the printing tape and the ink ribbon in a state placed one upon another, a platen shaft for rotating the platen, a ribbon take-up reel for taking up the ink ribbon, and a ribbon take-up shaft for rotating the ribbon take-up reel, the feed mechanism-side gear train including a platen gear on which the platen shaft is coaxially secured and a take-up gear on which the ribbon take-up shaft is coaxially secured, as respective output ends thereof.
According to this preferred embodiment, by rotating the platen shaft and the ribbon take-up shaft via the platen gear and the take-up gear, respectively, the printing tape and the ink ribbon can be properly fed together in a state placed one upon the other.
More preferably, the tape cutting mechanism includes a stationary blade and a movable blade that perform relative motion therebetween for cutting operation, and a crank disk for engaging with the movable blade to cause the movable blade to effect the cutting operation, and the cutting mechanism-side gear train includes a cutter gear coaxially secured to the crank disk as an output end of the cutting mechanism-side gear train.
According to this preferred embodiment, by rotating the crank disk via the cutter gear, it is possible to cause the movable blade to perform a proper cutting operation. It is preferable that the stationary blade and the movable blade form a cutter in the form of scissors.
Further preferably, the tape printing apparatus includes a tape exit from which the printed portion of the printing tape is discharged, and a tape holding mechanism associated with the tape exit and linked to the tape cutting mechanism, for holding the printed portion cut off by the tape cutting mechanism at the tape exit.
Still more preferably, the tape printing apparatus includes a control block for controlling the rotation of the motor, and the control block controls the rotation of the motor such that when the movable blade has reached a cutting terminal portion as an end position in a cutting direction of the movable blade by the rotation of the motor in the another of the normal and reverse directions, the printed portion is held at the tape exit by the tape holding mechanism.
Even further preferably, the tape printing apparatus includes a printing block for printing on the printing tape, the motor including a rotational shaft, the crank disk having a peripheral surface and a recess formed in the peripheral surface, the recess having an arcuate profile in cross-section, the control block including an encoder arranged in proximity to the rotational shaft of the motor, for detecting a rotational angle through which the rotational shaft of the motor rotates, and a detection switch in abutment with the peripheral surface of the crank disk, the detection switch moving into the recess when the movable blade has reached a cutting wait position, and generating a cutting wait position detection signal indicative of the cutting wait position of the movable blade, the control block causing the motor to rotate in the another of the normal and reverse directions in response to a print command to thereby cause the movable blade to be pivotally moved to the cutting wait position, and in response to the cutting wait position detection signal, causing the motor to rotate in the one of the normal and reverse directions to thereby cause the movable blade to be held at the cutting wait position and at the same time cause the tape feeding mechanism to feed the printing tape, and upon termination of the printing, the control block causing the motor to rotate in the another of the normal and reverse directions to cause the movable blade to be pivotally moved from the cutting wait position to the cutting terminal position until the encoder detects a predetermined rotational angle through which the rotational shaft of the motor has rotated when the movable blade has reached the cutting terminal position, and then causing the motor to stop to thereby cause the tape holding mechanism to hold the printed portion of the printing tape at the tape exit.
The above and other objects, features, and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.